Problem Decoding using Swift Codable

Question

Created Dec ’19

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I am new to Swift and not very experienced as a programmer in general. My question is what am I doing wrong with decoding data?

I seem to have no problem encoding and writing data to disk but when I read and decode that same data, it is having a problem.

import Foundation

class Person: Codable {
    var name: String
    
    init(name: String){
        self.name = name
    }
}

let aPerson = Person(name: "John")

let documentsDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
let archiveURL = documentsDirectory.appendingPathComponent("name_test").appendingPathExtension("plist")

let propertyListEncoder = PropertyListEncoder()
let encodedPerson = try? propertyListEncoder.encode(aPerson)

try? encodedPerson?.write(to: archiveURL)

let propertyListDecoder = PropertyListDecoder()
if let retrievedPersonData = try? Data(contentsOf: archiveURL),
    let decodedPerson = try? propertyListDecoder.decode(Person.self, from: retrievedPersonData) {
    print(decodedPerson)
}

The output is: __lldb_expr_X.Person

(where X is an odd number that will start at 1 and rise after every subsequent run).

Any ideas?

Answered by Claude31 in 398611022

Change line 24 into

    print(decodedPerson.name)

decodedPerson is the whole struct. So you need to access to the property itself.

in playground (I suppose that's where you tested), you'll get

decodedPerson John

instead of

__lldb_expr_17.Person

Would be the same with more complex struct:

class Person: Codable {
    var name: String
    var age: Int
     
    init(name: String, age: Int){
        self.name = name
        self.age = age
    }
}

        let aPerson = Person(name: "John Apple", age: 32)

            print(decodedPerson)
            print("decodedPerson", decodedPerson.name, decodedPerson.age)

will return (here from an app)

AppName.Person

decodedPerson John Apple 32

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Answer 1

Claude31 OP

Dec ’19

Accepted Answer